Earlier this year, we asked our readers to let us know what they believed to be the best sci-fi film of all time – and they certainly delivered, crowning Alien in the number 1 spot.
Now, we’ve returned to them, this time looking instead for the greatest sci-fi TV series of all time. Our post (via Facebook) has almost 1000 comments, with fans weighing in with the best of the best from the genre on the small screen.
Of course, sci-fi is extremely varied, and that has certainly shown up in the results, which we have sifted through to find the 10 most mentioned shows. The overall winner of the poll ended up being mentioned in almost one fifth of all comments.
Like our film poll before it, the results have seen no shows which began in the past decade show up in the top 10 – the most recent entry on the list began in 2015, while the oldest series started back in 1963 (if you’re a sci-fi fan, you probably know which one that is…)
Without further ado, here is the definitive list of the greatest sci-fi TV series of all time according to Radio Times readers, counting down to the overall winner.
10. Quantum Leap
Coming in 10th place, with 2.5 per cent of all mentions on the thread, is Quantum Leap, the 1989 US series starring Scott Bakula and Dean Stockwell. The series ran for five seasons, before a 2022 reboot picked up the gauntlet and ran for two seasons.
The show focused on Dr Sam Beckett, a physicist who tested a time travel device on himself, but instead found that it allowed him to transfer between the bodies of other people in the past. In order to return to his own time, he found he must change events in the past to correct things. Meanwhile, he was joined on his journey by a hologram of his best friend, Rear Admiral Al Calavicci.
Perhaps best-known for its earnest and heartfelt tone, the series remains a firm favourite of many sci-fi fans, and thus earns its place on our list.
9. Stargate
Coming in ninth place with 2.9 per cent of all mentions on the thread was the Stargate franchise, which kicked off on TV with Stargate SG-1 in 1997, following on from the 1994 feature film. Since then, there have been three more series in the franchise (plus one animated show which is often considered to be non-canonical), and as of November 2025 there is another new addition in the works.
A military sci-fi franchise, it follows various expeditionary teams and centres around the titular Stargate devices, which were created by an ancient alien species and allow instantaneous travel across space between any two of them on the network.
The fact that a new series is in works almost 30 years after SG-1 debuted tells you all you need to know about the show’s ongoing popularity – meaning its placement on this list is no surprise at all.
8. The Expanse
Garnering 3 per cent of all mentions on the thread, The Expanse is the most recent series to have debuted which features on the list. Starring the likes of Thomas Jane, Steven Strait and Dominique Tipper, the series ran for six seasons, and is based on the novels of the same name by James SA Corey.
It follows a group who find themselves at the centre of a conspiracy hundreds of years in the future, in a timeline where humanity has conquered the solar system. Praised for its complex political storytelling and its blending of sci-fi elements with detective noir, the series was saved from cancellation after its third run, and was able to cement its place on lists such as this by rounding out its story across three more seasons.
7. Battlestar Galactica
Few shows have had quite such a stop-start run as number 7 on our list, Battlestar Galactica, which garnered 4.2 per cent of all mentions on the thread. The franchise features an initial series which started in 1978, followed by a sequel series in 1980, a miniseries in 2003 followed by four more seasons running from 2004 to 2009. That’s not to mention prequel spin-off show Caprica.
What ties it all together is the setting and general premise, which sees a human civilisation, spread out across planets in the 12 colonies, in a war with a cybernetic race known as the Cylons. Following a devastating attack, human survivors flee aboard the Battlestar Galactica, looking for the fabled 13th colony – Earth.
With a political core but also plenty of fun on its surface, the series is known for its intimate human drama, alongside all the spectacle and flourishes.
6. Firefly
For sci-fi fans, Firefly so often does hold a special place in their hearts, not least because of how it was cut down in its prime. The series, which showed up in 4.3 per cent of all comments on the thread, ran for only one season, even though the story has been continued in expanded media, including follow-up film Serenity.
Starring the likes of Nathan Fillion, Gina Torres, Alan Tudyk and Morena Baccarin, the original series followed nine crew members aboard Firefly-class spaceship Serenity in the year 2517. Known for its beloved characters and complex explorations of political and moral quandaries, the series is still hugely popular to this day, so much so that an animated sequel series is finally in advanced development.
5. Babylon 5
J Michael Straczynski’s beloved space opera series, which ran from 1994 to 1998 and spawned a host of sequel films, was mentioned in 5.9 per cent of all comments on the thread. Known for featuring long-ranging, impactful story arcs, the series followed the human staff and alien diplomats on board the titular space station, which was created in the aftermath of multiple inter-species wars.
The series has had a long-lasting legacy and impact on the sci-fi genre as a whole, and often features on lists of the best ever cult shows.
4. Red Dwarf
The most outright comedic of all the shows on this list, cult British series Red Dwarf received 6.3 per cent of all mentions on the thread. It originally aired between 1988 and 1999 on BBC Two, before returning on Dave for follow-up seasons and specials between 2009 and 2020.
Co-created by Doug Naylor and the late Rob Grant, the series followed Dave Lister, the last living human who is stranded 3 million years in the future on board the titular spacecraft, after awakening from suspended animation. There, he finds he is on board the ship with a hologram of his former bunkmate Arnold Rimmer, a creature known as Cat, the sanitation droid Kryten and the ship’s computer Holly.
The show’s focus, structure and tone have changed over its long run, meaning fan reaction has been split at various point. However, what has remained is a love for the core tenets of the series and its central characters.
3. Blake’s 7
Earlier this year, it was reported that a reboot of Blake’s 7 was in development. Clearly, the team behind the new version of the show haven’t been overestimating its enduring popularity, as it appeared in 7.2 per cent of all mentions on the thread, coming third in our list of the great sci-fi TV shows of all time.
Running for four seasons between 1978 and 1981, the series was set hundreds of years in the future, and originally followed a political dissident, Roj Blake, leading a group of rebels against the totalitarian Terran Federation, rulers of Earth and other colonised planets. Having broken out of prison and escaping on a technologically advanced alien spacecraft, Blake and his new crew, the Seven, began an organised campaign to damage the Federation. In seasons 3 and 4, a character called Kerr Avon became the show’s focus, as he took over as leader from Blake.
As with many of the shows on this list, the series was best known for its hard-hitting political, ethical and social themes, with these managing to thoroughly make up for its oftentimes low production values.
2. Star Trek
One of the most globally renowned sci-fi franchises of all-time, Star Trek is still going strong with new additions to the canon today, after it kicked off with The Original Series in 1966. 15.2 per cent of all mentions on the thread referred to Star Trek, with Gene Roddenberry’s series still commanding a loyal army of fans to this day.
The Original Series followed the crew of the USS Enterprise, including William Shatner’s James T Kirk, Leonard Nimoy’s Spock and Nichelle Nichols’s Uhura. With a hopeful philosophy and groundbreaking storytelling, Star Trek has continued to “boldly go” in various forms for decades, and no doubt will continue to do so for a long time to come, given the love it still commands from viewers to this day.
1. Doctor Who
It was a close call between second and first place, but in the end the Time Lord took it home, with 17.7 per cent of all mentions on the thread. And is it really a surprise?
Doctor Who has been the BBC’s jewel in the crown and a British institution since it debuted in 1963 (minus those wilderness years which we don’t talk about).
The series, about a time travelling alien from the planet Gallifrey who handily changes his face when his life would otherwise be at its end, remains beloved to this day, with a Christmas special on the way in December.
Spawning a whole Whoniverse of spin-offs from Torchwood and The Sarah Jane Adventures to the most recent addition, The War Between the Land and the Sea, and with culturally ubiquitous iconography like the TARDIS and the Daleks, Doctor Who is a true titan of sci-fi, and a worthy winner.
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